Holds the entities, such as customer, product, store or date, by which facts are summarised in a snowflake or star schema. Users drill up and down through hierarchies of these dimensions.
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Terms in this definition
- Star schema
A model for analytics named after its diagram's shape: dimension tables describing the data surround, and link to, one central fact table holding the measures.
Related terms
- Degenerate dimension
Something like an order number that describes the data but has the same grain as the fact table, so it lives in the fact table instead of a dimension table of its own; a Power Query table or a view can expose it.
- lookup operator
A KQL operator for enriching a big fact table with columns from a small dimension table. Only leftouter (the default) and inner are allowed, key columns are not duplicated, and because the right-hand table is broadcast, one bigger than a few tens of MB causes the query to fail.
- Relationship cardinality
Describes whether the values on each side of a relationship are unique, giving one-to-one, one-to-many (many-to-one) or many-to-many. With one-to-many, the dimension table sits on the one side and the fact table on the many side.